Arcuate fixation member

ABSTRACT

Arcuate fixation members with varying configurations and/or features are provided, along with additional components for use therewith in provided intervertebral implants. The arcuate fixation members may be of different lengths, cross sectional geometries, and/or cross sectional areas. Applications of intervertebral implants utilizing arcuate fixation members are particularly suitable when a linear line-of-approach for delivering fixation members is undesirable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 15/898,991, filed Feb. 19, 2018, which is a continuation ofU.S. patent application Ser. No. 15/060,566, filed Mar. 3, 2016, nowU.S. Pat. No. 9,925,056, issued Mar. 27, 2018, which is a continuationof U.S. patent application Ser. No. 14/148,949, filed Jan. 7, 2014, nowU.S. Pat. No. 9,445,913, issued Sep. 20, 2016, which is a continuationof U.S. patent application Ser. No. 13/070,883, filed Mar. 24, 2011, nowU.S. Pat. No. 8,641,766, issued Feb. 4, 2014, which is acontinuation-in-part of and claims priority to U.S. patent applicationSer. No. 12/761,101, filed Apr. 15, 2010, now U.S. Pat. No. 9,408,715,issued Aug. 9, 2016, which claims priority to U.S. Provisional PatentApplication No. 61/169,461, filed Apr. 15, 2009. The disclosures of eachapplication listed in this paragraph are hereby incorporated byreference as if set forth in their entireties herein.

TECHNICAL FIELD

The present disclosure relates generally to orthopedics, and inparticular relates to fixation systems, intervertebral implants, andassociated surgical methods and procedures for using same.

BACKGROUND

Spinal fixation systems such as pedicle screw and rod constructs arecommonly used to promote fusion between intervertebral bodies. Theinsertion of pedicle screws typically requires a linear“line-of-approach” trajectory that is aligned with the longitudinal axisof the screw, in order to accommodate the access and deliveryinstruments. Similarly, anchors such as bone screws may be used todirectly fix intervertebral implants to vertebral bodies, typicallyrequiring the insertion of several screws at unique angles oblique tothe sagittal and/or transverse plane, and thus multiplelines-of-approach. However, in a variety of surgical situations,achieving a desired trajectory for screw insertion can be difficult dueto the patient's anatomy obstructing a linear line-of-approach. Forexample, medially-directed placement of pedicle screws into the sacrumis desirable to prevent screw loosening and/or pullout, but can beprohibited due to the iliac crest obstructing the linearline-of-approach.

SUMMARY

In accordance with one embodiment, a bone fixation member configured tobe inserted in a vertebral body includes a fixation body having opposingproximal and distal ends and a curved intermediate portion extendingbetween the proximal and distal ends. A tip configured to cut into boneis defined at the distal end. A guidance member is disposed at the tipand extends toward the proximal end of the body. The guidance member isconfigured to guide the tip along an insertion trajectory as thefixation member is inserted into a vertebral body.

The bone fixation member can be used with an intervertebral implant thatincludes a spacer body that is configured to be implanted into anintervertebral space. The spacer body has an outer wall that defines atleast a first aperture extending into the spacer body. Theintervertebral implant also includes an insert that defines a plate. Theinsert is configured to be coupled to the spacer body such that theinsert and the outer wall of the spacer body define a second aperturetherebetween.

An alternative intervertebral implant that can be used with the bonefixation member includes a spacer body that has upper and lower platesand an outer wall extending between the upper and lower plates. Thespacer body has a plurality of apertures extending through each of theupper and lower plates. The intervertebral implant also includes aninsert that defines a plate. The insert is configured to be coupled tothe spacer body such that the insert is disposed opposite at least aportion of the outer wall.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe preferred embodiments of the application, will be better understoodwhen read in conjunction with the appended drawings. For the purposes ofillustrating the arcuate fixation member and intervertebral implants foruse therewith, there are shown in the drawings preferred embodiments. Itshould be understood, however, that the instant application is notlimited to the precise arrangements and/or instrumentalities illustratedin the drawings, in which:

FIG. 1A is a side elevation view of an arcuate fixation memberconstructed in accordance with an embodiment;

FIG. 1B is a perspective view of the arcuate fixation member illustratedin FIG. 1A;

FIG. 2A is a top elevation view of an intervertebral implant spacer foruse with arcuate fixation members, constructed in accordance with anembodiment;

FIG. 2B is a front elevation view of the intervertebral implant spacerillustrated in FIG. 2A;

FIG. 2C is a side elevation view of the intervertebral implant spacerillustrated in FIG. 2A;

FIG. 3A is a front elevation view of an insert plate for use with theintervertebral implant spacer illustrated in FIGS. 2A-C;

FIG. 3B is a top elevation view of the insert plate illustrated in FIG.3A;

FIG. 4A is a front elevation view of a blocking plate for use with theinsert plate illustrated in FIGS. 3A-B;

FIG. 4B is a top elevation view of the blocking plate illustrated inFIG. 4A;

FIG. 4C is a front elevation view of a blocking plate similar to theblocking plate illustrated in FIG. 4A, but constructed in accordancewith an alternative embodiment;

FIG. 5 is a side elevation view of a locking screw for use with theinsert plate and blocking plate illustrated in FIGS. 3A-B and 4A-B,respectively;

FIG. 6A is an exploded view of an intervertebral implant assemblyconstructed from the intervertebral implant system componentsillustrated in FIGS. 1A-5 ;

FIG. 6B is a perspective view of the intervertebral implant assemblyillustrated in FIG. 6A, in an assembled configuration;

FIG. 6C is a side elevation view of the intervertebral implant assemblyillustrated in FIG. 6B, inserted into an intervertebral space;

FIG. 7A is a side elevation view of an arcuate fixation memberconstructed in accordance with an alternative embodiment;

FIG. 7B is a front perspective view of the arcuate fixation memberillustrated in FIG. 7A;

FIG. 7C is a rear elevation view of the arcuate fixation memberillustrated in FIG. 7A;

FIG. 7D is a rear perspective view of the arcuate fixation memberillustrated in FIG. 7A;

FIG. 7E is a front perspective view of a portion of the arcuate fixationmember in FIG. 7A, showing a guidance member;

FIG. 7F is a rear perspective view of the portion of the arcuatefixation member in FIG. 7E;

FIG. 7G is a top elevation view of the arcuate fixation memberillustrated in FIG. 7A;

FIG. 7H is a sectional front elevation view of the arcuate fixationmember illustrated n FIG. 7G, taken along line 7H-7H;

FIG. 7I is a rear elevation view of an arcuate fixation member similarto the arcuate fixation member illustrated in FIG. 7A, but constructedin accordance with an alternative embodiment;

FIG. 7J is a rear perspective view of the arcuate fixation memberillustrated in FIG. 7I;

FIG. 8A is a top elevation view of an intervertebral implant spacer foruse with arcuate fixation members, constructed in accordance with analternative embodiment;

FIG. 8B is a perspective view of the intervertebral implant spacerillustrated in FIG. 8A;

FIG. 8C is a front elevation view of the intervertebral implant spacerillustrated in FIG. 8A;

FIG. 8D is a side elevation view of the intervertebral implant spacerillustrated in FIG. 8A;

FIG. 9A is a top elevation view of an intervertebral implant spacer foruse with arcuate fixation members, constructed in accordance withanother alternative embodiment;

FIG. 9B is a perspective view of the intervertebral implant spacerillustrated in FIG. 9A;

FIG. 9C is a front elevation view of the intervertebral implant spacerillustrated in FIG. 9A;

FIG. 9D is a side elevation view of the intervertebral implant spacerillustrated in FIG. 9A;

FIG. 10A is a top elevation view of an insert plate for use with theintervertebral implant spacers illustrated in FIGS. 8A-D and 9A-D;

FIG. 10B is a front elevation view of the insert plate illustrated inFIG. 10A;

FIG. 10C is a rear elevation view of the insert plate illustrated inFIG. 10A;

FIG. 10D is a perspective view of the insert plate illustrated in FIG.10A;

FIG. 10E is a top elevation view of the insert plate illustrated in FIG.10A, constructed in accordance with an alternative embodiment;

FIG. 10F is a top elevation view of the insert plate illustrated in FIG.10A, constructed in accordance with another alternative embodiment;

FIG. 11A is a top elevation view of an intervertebral implantconstructed with an alternative embodiment of the intervertebral implantspacer illustrated in FIGS. 8A-D and the insert plate illustrated inFIGS. 10A-D;

FIG. 11B is a sectional elevation view of the intervertebral implantillustrated in FIG. 11A, taken along line 11B-11B;

FIG. 12A is a top elevation view of the intervertebral implantillustrated in FIG. 11A, constructed in accordance with an alternativeembodiment;

FIG. 12B is a top elevation view of the intervertebral implantillustrated in FIG. 11A, constructed in accordance with anotheralternative embodiment;

FIG. 12C is a top elevation view of the intervertebral implantillustrated in FIG. 11A, constructed in accordance with still anotheralternative embodiment;

FIG. 13A is a side elevation view of an intervertebral implantconstructed in accordance with an embodiment; and

FIG. 13B is a side elevation view of the intervertebral implantillustrated in FIG. 12A, constructed in accordance with anotherembodiment.

FIG. 14A is an exploded view of an intervertebral implant constructedfrom the intervertebral implant system components illustrated in FIGS.7A-8D and 10A-D; and

FIG. 14B is a perspective view of the intervertebral implant illustratedin FIG. 14A, in an assembled configuration.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right”, “left”, “top” and “bottom”designate directions in the drawings to which reference is made. Thewords “inwardly” and “outwardly” refer to directions toward and awayfrom, respectively, the geometric center of the device and designatedparts thereof. The words, “anterior”, “posterior”, “superior”,“inferior”, “lateral”, “medial”, “sagittal”, “axial”, “coronal,”“cranial,” “caudal” and related words and/or phrases designate preferredpositions and orientations in the human body to which reference is madeand are not meant to be limiting.

The words “arcuate” and “curved” as used herein refer generally to thevarying physical geometry of an object along an axis coincident to theobject, for example the deviation from straightness of the body of anarcuate fixation member along a central longitudinal axis defined withinthe body of the object between its proximal and distal ends. Generally,with reference to a straight axis projected from a first end of such anobject, as distance from the first end of the object increases along thecentral longitudinal axis of the object, distance between the centrallongitudinal axis of the object and the straight axis increases more orless continuously, so that the body of the object defined along itscentral longitudinal axis takes on a curved or arcuate shape. Theresulting curvature of the central longitudinal axis may exhibit aconstant or uniform radius with respect to a point in space definedremotely from the body of the object. Alternatively, a non-uniform orvarying radius of curvature may be defined. The curvature of the body ofthe object defined by the longitudinal axis may also vary in directionwith respect to a Cartesian coordinate system. The curvature may beuniformly distributed along the body of the object, for example betweenthe proximal and distal ends of the object, or may be localized withinone or more distinct segments of the body of the object. The curvatureof the object may be significantly smooth and continuous along itscentral longitudinal axis, may be defined by a series of straightinterconnected segments where each successive segment defines anincreasing angle between the central longitudinal axis of the body ofthe object and the straight axis, or any combination thereof.

The words “vertebral body” as used herein should be interpreted broadlyto include all the bones and bony structures found within and in theimmediate proximity of the human spinal system, including but notlimited to those found in the cervical region, the thoracic region, thelumbar region, and the sacral curve region.

The terminology intended to be non-limiting includes the above-listedwords, derivatives thereof and words of similar import.

Referring initially to FIGS. 1A-6C, example embodiments of components ofan intervertebral implant system 100 comprising a bone fixation memberwhich can define an arcuate fixation member 12C as illustrated, anintervertebral implant spacer 108, an insert plate 116, a blocking plate132, and a locking screw 138 are illustrated. Applications of theintervertebral implant system 100 could include, but are not limited to,fixation of the endplate components of a total disc replacement tovertebral bodies, direct fixation of an intervertebral implant tovertebral bodies, fixation into osteoporotic bone, and the like. The useof the systems and/or methods utilizing arcuate fixation membersdisclosed herein are particularly suitable when a linearline-of-approach for delivering a fixation member is undesirable. Itshould be noted that the physical characteristics of the arcuatefixation members disclosed herein may cause them to be alternatelydescribed as curved fixation members, arcuate or curved blades, arcuateor curved pins, arcuate or curved nails, or other terms of similardescriptive import.

As will become appreciated from the description below, one or morefixation members 12C may be utilized to securely anchor an assembledconfiguration of intervertebral implant system 100 within anintervertebral space between adjacent vertebral bodies. Unless otherwiseindicated, the intervertebral implant system 100 and its components canbe manufactured from any suitable biocompatible material known in theart including but not limited to titanium, titanium alloy such as TAN,commercially pure titanium, stainless steel, tantalum, polymers such aspolyether ether ketone (PEEK), reinforced plastics, allograft bone, andthe like.

Referring now to FIGS. 1A-B, the arcuate fixation member 12C includes abody 102 defining a proximal end 102 a and a distal end 102 b oppositethe proximal end. The distal end 102 b may comprise a tip 104 configuredto cut into underlying structure or bone. The body 102 may furtherdefine an intermediate portion between the proximal end 102 a and thedistal end 102 b that is curved along a central curved axis L1. In anembodiment, the intermediate portion is curved along substantially theentire length of the body 102 between the proximal end 102 a and thedistal end 102 b. Alternatively, one or more distinct portions of theintermediate portion between the proximal end 102 a and the distal end102 b may be curved (not shown).

In the illustrated embodiment, the intermediate portion is curved alongthe central curved axis L1 in accordance with a uniform radius ofcurvature R1. Alternatively, the intermediate portion may define anon-uniform radius of curvature along the central curved axis L1. In apreferred embodiment, the curvature of the intermediate portion may besmooth and continuous. Alternatively, the curvature of the intermediateportion may be defined by a series of substantially straight sections(not shown), with each substantially straight section aligned along anindividual longitudinal axis corresponding to the individual section,where the magnitude of an angle α with respect to a perpendicularreference axis extended from the proximal end 102 a increases inmagnitude with the distance of each subsequent straight section from theproximal end 102 a.

The arcuate fixation member 12C may have a head 106 defined at theproximal end 102 a of the body 102. The head 106 may extend radiallyoutward from the proximal end 102 a of the body 102 in a directionperpendicular to the longitudinal axis L1. In an example embodiment, thehead 106 may extend from the body 102 in a direction generally oppositefrom the direction of curvature of the body 102, as depicted in FIGS.1A-B. In alternative embodiments, the head 106 may extend from the body102 in a direction generally towards the direction of curvature of thebody 102. The head may define an upper surface 106 a configured formulti-angular engagement with a complementary surface of a deliveryinstrument, and a lower surface 106 b opposite the upper surface 106 aand configured to engage another component of the intervertebral implantsystem 100, for example the insert plate 116, when the arcuate fixationmember 12C is in a fully inserted position.

Referring now to FIGS. 2A-C, the intervertebral implant spacer, orspacer 108 is defined by a posterior side 108 a, an anterior side 108 bopposite the posterior side, lateral sides 108 c, an upper surface 108d, and a lower surface 108 e opposite the upper surface. In an exampleembodiment, a portion of the posterior side 108 a between the lateralsides 108 c may be curved inwardly in the direction of the anterior side108 b, defining a rounded, generally rectangular kidney-like footprint,as depicted in FIG. 2A. In an alternative embodiment, a portion of theposterior side 108 a between the lateral sides 108 c may be curvedoutwardly in a direction away from the anterior side 108 b (not shown).In another alternative embodiment, the posterior side 108 a may besubstantially straight between the lateral sides 108 c, defining arounded, generally rectangular footprint (not shown). The spacer 108 mayhave a central bore 110 defined therethrough, the shape of whichsubstantially conforms to the footprint of the spacer 108 (e.g., arounded, generally rectangular kidney-like footprint, or a rounded,generally rectangular footprint, depending upon the geometry of theposterior side 108 a). The central bore 110 can be filled with bonegrowth inducing substances to allow bony ingrowth and to assist infusion between the spacer 108 and adjacent vertebral bodies.

In an example embodiment of the spacer 108, the upper and lower surfaces108 d and 108 e may have gripping structures 108 h such as teeth,spikes, or similar structures, defined thereon and configured tofacilitate gripping engagement between the upper and lower surfaces 108d and 108 e and the end plates of adjacent vertebral bodies. The teeth112 may be pyramidal, saw toothed or other similar shapes. Inalternative embodiments of the spacer 108, portions of and/or theentirety of the upper and lower surfaces 108 d and 108 e may besubstantially smooth and devoid of any protrusions. Upper and loweredges 108 f and 108 g, defined where the upper and lower surfaces 108 dand 108 e intersect with the posterior, anterior, and lateral sides 108a, 108 b, and 108 c respectively around the outer perimeter of thespacer 108, may be rounded (not shown). In an example embodiment, theupper and lower edges 108 f and 108 g may be rounded using a uniformradius of curvature around the perimeter of the implant. In analternative embodiment, the upper and lower edges 108 f and 108 g may berounded using a non-uniform radius of curvature around the perimeter ofthe implant. In another alternative embodiment, the upper and loweredges 108 f and 108 g along the anterior side 108 b may be rounded witha greater radius than the remainder of the upper and lower edges 108 fand 108 g, such that a bull nose outer surface (not shown) is created onthe anterior side 108 b of the implant. Rounding upper and lower edges108 f and 108 g may facilitate easier insertion of the spacer 108, forexample by minimizing required distraction of the end plates of adjacentvertebral bodies.

In an example embodiment, the spacer 108 has a generally wedge-shapedside-view profile. As illustrated in FIG. 2C, this wedge shape isdefined by a gradual decrease in the height of the spacer 108 (asmeasured between the upper and lower surfaces 108 d and 108 e) extendingbetween the posterior side 108 a in the direction of the anterior side108 b. The spacer 108 has a generally constant height between lateralsides 108 c. In alternative embodiments, the spacer 108 may have agradual increase in height followed by a gradual decrease in heightextending from one lateral side 108 c to the other, and/or may have agenerally constant height between the posterior and anterior sides 108 aand 108 b, or may have convex and/or concave upper and lower surfaces108 d and 108 e, thereby defining a gradual increase in height followedby a gradual decrease in height extending from the posterior side 108 ato the anterior side 108 b and from one lateral side 108 c to the other.

A plurality of grooves 112 may be defined on the spacer 108 where theupper and lower surfaces 108 d and 108 e intersect with the anteriorside 108 b. The grooves 112 may be concave and may be configured toalign with arcuate grooves 128 of the insert plate 116 when the spacer108 and the insert plate 116 are in an assembled configuration. In anexample embodiment, the grooves 112 may be substantially smooth anddevoid of any protrusions. Retaining grooves 114 may be defined withinthe lateral sides 108 c of the spacer 108 between the upper and lowersurfaces 108 d and 108 e. The retaining grooves 114 may be configured toreleasably engage complementary engaging ribs 120 of the insert plate116.

Referring now to FIGS. 3A-B, the fixation plate, or insert plate, orinsert 116 is defined by a generally C-shaped, channel-like body 118that includes an anterior side 118 a with upper and lower sides 118 band 118 c opposite each other, and lateral sides 118 d extending fromopposite sides of the anterior side 118 a in a generally perpendiculardirection from the anterior side 118 a. The anterior, upper, lower, andlateral sides 118 a, 118 b, 118 c, and 118 d may form a generallychannel-like structure (in essence, a cradle) which may be configured toreceive the anterior side 108 b and at least a portion of the lateralsides 108 c in partial nested engagement. As such, the upper and lowersides 108 b and 108 c may define gradual increases and/or decreases inheight in a posterior direction from the anterior side 118 a and/orbetween the lateral sides 108 d, in order to generally conform theinsert plate 116 to the geometry of the spacer 108. The lateral sides118 d may have engaging ribs 120 defined thereon at the ends oppositethe anterior side 118 a, the engaging ribs 120 configured to bereleasably received within the retaining grooves 114 of the spacer 108.

The anterior side 118 a of the insert plate 116 may have a pair ofapertures 122 defined therethrough configured to receive graspingmembers of a delivery instrument. In an example embodiment, theapertures 122 may be D-shaped, as illustrated in FIG. 3A. However anyother aperture shape may be defined as appropriate. The apertures 122may have a retaining rib 124 defined therein configured to engage with acomplementary grasping rib of the delivery instrument. The anterior side118 a of the insert plate 116 may also have a central bore 126 definedtherethrough having an inner surface 126 a with threads configured toengage complementary threads of a locking screw 138. The anterior side118 a of the insert plate 116 may also have a concave recess 130 definedtherein configured to receive a complementary convex surface 134 d ofthe blocking plate 132.

The anterior side 118 a of the insert plate 116 may also have aplurality of arcuate grooves 128 defined therethrough configured toslidably receive the arcuate fixation members 12C and to define aninsertion trajectory for each of the arcuate fixation members 12C. In anexample embodiment, the arcuate grooves 128 may have a generally uniformcross sectional geometry configured to closely conform to the crosssectional geometry of the body 102 of the arcuate fixation member 12Cbetween the head 106 and the distal end 102 b. When an arcuate fixationmember 12C is in a fully inserted position within a respective arcuategroove 128, the lower surface 106 b of the head 106 will be engaged withthe outer surface of the anterior side 118 a of the insert plate 116.Because the upper surface 106 a of the head 106 will not be flush withthe outer surface of the anterior side 118 a of the insert plate 116 inthis configuration, it may be desirable to omit the blocking plate 132and the locking screw 138. In an alternative embodiment, the arcuategrooves 128 have a recessed ledge defined therein in the area where thearcuate grooves 128 intersect with the outer surface of the anteriorside 118 a of the insert plate 116, the recessed ledge being configuredto receive the lower surface 106 b of the head 106 when the arcuatefixation member 12C is in a fully inserted position, such that the uppersurface 106 a of the head 106 is substantially flush with the outersurface of the anterior side 118 a of the insert plate 116.

The arcuate grooves 128 may be disposed about the central bore 126 inany desired configuration and may define any insertion trajectories asappropriate. In the example embodiment depicted in FIGS. 3A-B, thearcuate grooves 128 are defined in opposing quadrants around the centralbore 126, with two arcuate grooves 128 located near the upper side 118 band defining two generally cranial insertion trajectories, and twoarcuate grooves 128 located near the lower side 118 c and defining twogenerally caudal insertion trajectories. It should be noted that thisconfiguration of arcuate groove 128 locations and arcuate fixationmember 12C insertion trajectories is merely an example, and the scope ofthe instant disclosure should not be limited thereto.

Referring now to FIGS. 4A-B, the blocking plate 132 is defined by agenerally disc-shaped body 134 with upper and lower surfaces 134 a and134 b that can be planar as illustrated, an anterior surface 134 c, anda posterior surface 134 d. The disc-shaped body 134 can further defineopposed side surfaces 135 a and 135 b, which can be convexly curved,extending between the upper and lower surfaces 134 a-b. The upper andlower surfaces 134 a and 134 b and the height of the body 134 (asmeasured between the upper and lower surfaces 134 a and 134 b) may bedefined to match the height (as measured between the upper and lowersurfaces 118 b and 118 c) of the anterior side 118 a of the insert plate116 when the blocking plate 132 is in a fully assembled configuration.The anterior surface 134 c of the body 134 may be generally planar, ormay be defined to match the outer surface of the anterior side 118 a ofthe insert plate 116 when the blocking plate 132 is in a fully assembledconfiguration. The posterior surface 134 d may be defined as a convexsurface configured to engage with the concave recess 130 of the insertplate 116 when the blocking plate 132 is in a fully assembledconfiguration.

The posterior surface 134 d can also be configured to engage the heads106 of the arcuate fixation members 12C inserted into the arcuategrooves 128 of the insert plate 116. For example, the posterior surface134 d can operate to drive the arcuate fixation members 12C into a fullyinserted position within the insert plate 116 as the locking screw 138is tightened. In addition to driving the arcuate fixation members 12Cinto a fully inserted position, the blocking plate 138 can additionallyprevent backout of the arcuate fixation members 12C. It should beappreciated that the posterior surface 134 d of the blocking plate 132is not limited to the illustrated convex surface, and that the posteriorsurface 134 d can define alternative geometries. For example, theposterior surface 134 d may define a plurality of angled surfaces, suchas four angled surfaces in opposed quadrants of the posterior surface134 d, each of the angled surfaces configured to engage with the head106 of a corresponding arcuate fixation member 12C.

The body 134 may have an aperture 136 defined therethrough. In anexample embodiment, the diameter of the aperture 136 may be slightlylarger than the diameter of the central bore 126 of the insert plate116, such that a locking screw 138 may be inserted into the aperture 136with no interference therebetween. In another embodiment, the diameterof the aperture 136 may be substantially the same as that of the centralbore 126, and the inner surface of the aperture 136 may have threadsdefined thereon, the threads configured to engage complementary threadsof the locking screw 138. The aperture 136 may further be defined by aconcave recess 136 a defined within the anterior surface 134 c, theconcave recess 136 a configured to receive the convex head 142 of thelocking screw 138.

It should be appreciated that the blocking plate 132 can begeometrically configured as desired so as to be received and nest in theconcave recess 362 and coupled to the insert plate 350. For instance,referring to FIG. 4C, the upper and lower surfaces 134 a-b of thedisc-shaped body 134 can be curved, and bow outwards in accordance withone embodiment. Furthermore, the side surfaces 135 a-b can extendsubstantially straight between the upper and lower surfaces 134 a-b. Thedisc-shaped body 134 can further define beveled surfaces 137 a-d thatare connected between respective side surfaces 135 a and 135 b andrespective upper and lower surfaces 134 a and 134 b. Pockets 139 a-b canbe defined extending into the side surfaces 135 a-b, the pockets 139 a-bconfigured to receive a driving instrument that braces against theblocking plate 132 so as to drive the locking screw 138 into the insertplate 350.

Referring now to FIG. 5 , the locking screw 138 includes a shaft 140that defines longitudinally opposing proximal and distal ends 140 a and140 b, respectively, and a head 142 coupled to the proximal end 140 a ofthe shaft 140, either directly or indirectly via an unthreaded neck 144that is coupled between the proximal end 140 a of the shaft 140 and thehead 142. The head 142 can define a generally convex shape between theinterface of the head 142 and the neck 144 that extends outward towardsa proximal end 142 a of the head 142. The convex shape of the head maybe configured to engage the concave recess 136 a of the blocking plate132. Of course, the head 142 can assume any other suitable alternativeshape as appropriate. Helical threads 146 extend radially out from theshaft 140 at locations at and between the proximal and distal ends 140 aand 140 b that are configured to engage complementary threads on theinner surface 126 a of the central bore 126 of the insert plate 116.Thus, a substantial entirety of the shaft 140 between the proximal anddistal ends 140 a and 140 b may be threaded. The distal end 142 a of thehead 142 may have driving members 142 b defined therein, designed toengage with complementary driving members of a delivery instrument. Itshould be appreciated that the locking screw 138 can alternatively beprovided in combination with the blocking plate 132 as a captive lockingscrew, wherein the locking screw 138 is rotatably retained within theaperture 136 of the blocking plate 132. It should be appreciated thatthe head 142 can be externally threaded.

Referring now to FIGS. 6A-C, an example embodiment of the intervertebralimplant system 100 is illustrated in an exploded view and in a nearlycompletely assembled configuration. FIG. 6B depicts the intervertebralimplant system 100 partially assembled outside of an intervertebralspace (the blocking plate 132 and locking screw 138 have been omittedfor simplicity). The spacer 108 has been seated within the insert plate116 such that the retaining ribs are seated with the retaining grooves114 on the lateral sides of the spacer 108. Four arcuate fixationmembers 12C have been inserted through corresponding arcuate grooves 128within the insert plate 116, and have been driven to an almost fullyinserted position. In a final assembled configuration, the arcuatefixation members 12C would be driven into their fully inserted position,the blocking plate 132 would be received within the concave recess 130in the anterior side of the insert plate 116, and the locking screw 138would be driven into the central bore 126 of the insert plate 116 andfinally tightened, thereby blocking the arcuate fixation members 12Cfrom backing out of the assembled intervertebral implant system 100.

FIG. 6C depicts an example embodiment of the intervertebral implantsystem 100 partially assembled inside of an intervertebral space betweenadjacent vertebral bodies V6 and V7 (the blocking plate and lockingscrew have been omitted for simplicity). As an initial step, the spacer108 has been prepared for insertion, for example by being packed a withbone growth inducing substance and or/having its outer surfaces properlyprepared, and has been seated within the insert plate 116 such theretaining ribs are seated with the retaining grooves on the lateralsides of the spacer 108. The spacer 108 was then inserted into theintervertebral space between the adjacent vertebral bodies V6 and V7using a delivery instrument (not shown). The delivery instrument wasthen used to deliver the four arcuate fixation members 12C into thearcuate grooves in the fixation plate 116 and drive them into an almostfully inserted position. During the final steps of the assembly process,the delivery instrument would be used to drive the arcuate fixationmembers 12C into their fully inserted position, the blocking plate wouldbe received within the concave recess in the anterior side of the insertplate 116, and the locking screw would be driven into the central boreof the insert plate 116 and finally tightened, thereby blocking thearcuate fixation members 12C from backing out of the assembledintervertebral implant system 100.

Now referring generally to FIGS. 7A-14B, alternative example embodimentsof components of the intervertebral implant system 100, for instancearcuate fixation member 12D, intervertebral implant spacers 316 and 336,and insert plate 350, are illustrated. Various embodiments of anintervertebral implant 400 can be constructed from the components of theintervertebral implant system 100, as described in more detail below. Itshould be noted preliminarily that in the interest of brevity, thefigures and subsequent description pertaining to the arcuate fixationmember 12D do not refer to certain features and/or uses of the arcuatefixation member 12C that may be integrated into the arcuate fixationmember 12D, for example the use of the arcuate fixation member 12C incombination with above-described components of the intervertebralimplant system 100, for instance the intervertebral implant spacer 108,the insert plate 116, the blocking plate 132, or the locking screw 138.However, embodiments in which those and other features of the arcuatefixation member 12C are integrated into the arcuate fixation member 12Dare intended to be within the scope of the instant disclosure.

Referring now to FIGS. 7A-J, an alternative embodiment of the arcuatefixation member is illustrated. The arcuate fixation member 12D includesa fixation body, or body 300 defining a proximal end 300 a, a distal end300 b opposite the proximal end, and an intermediate portion 300 cextending between the proximal and distal ends 300 a-b, respectively.The fixation body 300 has a cross sectional geometry that issubstantially hexagonal, defining opposing laterally convex front andrear surfaces 300 e-f extending between opposing sides, or edges 300 d.The fixation body 300 defines a cross sectional geometry that issubstantially constant throughout the intermediate portion 300 c of thefixation body 300, and is tapered between lateral surfaces 301converging along the edges 300 d near the distal end 300 b, defining atip 302 configured to cut into an underlying structure, such as bone.The intermediate portion 300 c of the fixation body 300 is curved alonga central curved axis L1. It should be appreciated that the centralcurved axis L1 can define an insertion trajectory of the arcuatefixation member 12D into underlying structure, such as a vertebral body.It should be appreciated that the insertion trajectory can bedifferently defined, for example in accordance with alternativegeometries of the arcuate fixation member 12D. In an embodiment, theintermediate portion 300 c is curved along substantially the entirelength of the fixation body 300 between the proximal and distal ends 300a-b, respectively. Alternatively, one or more distinct portions of theintermediate portion 300 c can be curved (not shown).

In the illustrated embodiment, the intermediate portion 300 c is curvedalong the central curved axis L1 in accordance with a uniform radius ofcurvature R1. Alternatively, the intermediate portion 300 c can define anon-uniform radius of curvature along the central curved axis L1. In apreferred embodiment, the curvature of the intermediate portion 300 cmay be smooth and continuous. Alternatively, the curvature of theintermediate portion 300 c can be defined by a series of substantiallystraight sections (not shown), with each substantially straight sectionaligned along an individual longitudinal axis corresponding to therespective individual section, where the magnitude of an angle α withrespect to a perpendicular reference axis A extended from the proximalend 300 a increases in magnitude with the distance of each subsequentstraight section from the proximal end 300 a. It should be appreciatedthat the cross sectional geometry of the fixation body 300 is notlimited to the illustrated substantially hexagonal shape, and that thefixation body 300 can alternatively be defined with any suitable crosssectional geometry. It should further be appreciated that the crosssectional dimension of the fixation body 300 may vary, for exampleincreasing or decreasing, throughout one or more portions of theintermediate portion 300 c.

The arcuate fixation member 12D may have a head 304 defined at theproximal end 300 a of the fixation body 300. The head 304 may extendradially outward from the proximal end 300 a of the fixation body 300 ina direction perpendicular to the central curved axis L1. In an exampleembodiment, the head 304 may extend from the fixation body 300 in adirection generally towards the direction of curvature of the fixationbody 300, as depicted in FIGS. 7A-D. In alternative embodiments, thehead 304 may extend from the fixation body 300 in a direction generallyopposite from the direction of curvature of the fixation body 300. Thehead 304 may define an upper surface 304 a configured for multi-angularengagement with a complementary surface of a delivery instrument, and alower surface 304 b opposite the upper surface 304 a and configured toengage another component of the intervertebral implant system 100, forexample the insert plate 350, when the arcuate fixation member 12D is inan inserted position. The head 304 can have one or more taperedsurfaces, for instance surface 304 c, defined thereon, the taperedsurface 304 c configured to engage with a complementary surface inanother component of the intervertebral implant system 100, for examplethe insert plate 350, thereby locking the arcuate fixation member 12D inan inserted position.

The fixation body 300 can define one or more guidance members, theguidance members configured to guide the tip 302 along an insertiontrajectory as the arcuate fixation member 12D is inserted into anunderlying structure, such as a vertebral body. In the illustratedembodiments, guidance members are disposed at distal end 300 b of thefixation body 300, and in particular near the tip 302, but canalternatively be defined at any location on the fixation body 300. Thefixation body 300 can define guidance members that are recessed withinthe fixation body 300, such as the illustrated flutes 306, or guidancemembers that comprise projections extending from the fixation body 300,such as the illustrated outer wings 303 and/or the keel 308, in anycombination. For example, in the illustrated embodiment, a pair ofrecessed guidance flutes, or flutes 306 are defined by a keel 308disposed between opposing wings 303.

The illustrated flutes 306 are defined by and are disposed at the tip302 of the fixation body 300, the flutes 306 extending into the fixationbody 300 from the tip 302 along directions substantially parallel toeach other and to the insertion trajectory of the arcuate fixationmember 12D, and terminating in the intermediate section 300 c of thefixation body 300 proximal from the tip 302. In alternative embodiments,the flutes 306 can extend along directions that are angularly offset orotherwise non-parallel with respect to each other and/or with respect tothe insertion trajectory. The flutes 306 are not limited to theillustrated length, and can alternatively be defined to terminate withinthe tip 302 of the fixation body, or to extend along any length, up tothe entirety, of the fixation body 300. It should be appreciated thatthe flutes 306 can be symmetrically with respect to each other asillustrated, or asymmetrically. For example the flutes 306 can bedefined with matching or different geometries, equal or differentlengths, equal or different depths, etc.

The illustrated flutes 306 have a substantially “V” shaped geometrydefined by outer wings, or wings 303 defined in the fixation body 300and inner surfaces, or keel surfaces 305 defined in the fixation body300, the wings 303 and keel surfaces 305 converging in troughs 307. Thekeel surfaces 305 define a keel 308, as described in more detail below,the flutes 306 are disposed between respective wings 303 and the keel308. It should be appreciated that the wings 303 are not limited to theillustrated offset wings 303 disposed adjacent the keel 308 onrespective sides of the keel 308, and that a single, up to a pluralityof wings 303 can be defined at any location in the fixation body 300,for example substantially centrally between the edges 300 d, offsetlaterally toward either edge 300 d, or substantially along either edge300 d. It should further be appreciated that the wings 303 and/or thekeel surfaces 305 are not limited to being defined within the crosssectional geometry of the fixation body 300, and can alternatively bedefined to extend outwardly from the fixation body 300, for example fromthe front or rear surfaces 300 e-f and/or the edges 300 d. It shouldfurther still be appreciated that the geometries of the flutes 306 arenot limited to the illustrated “V” shape, and can alternatively bedefined with any suitable geometry.

The keel surfaces 305 define a projection from the fixation body 300,the projection configured as a guidance member in the form of a guidancekeel, or keel 308. In the illustrated embodiment, the keel 308 isdefined substantially centrally between the edges 300 d of the fixationbody 300, and disposed between the wings 303. In alternativeembodiments, the keel 308 can be laterally offset toward either edge 300d. It should be appreciated that the arcuate fixation member 12D is notlimited to a single keel 308 as illustrated, and that the fixation body300 can define a plurality of keels 308 at any locations in the fixationbody 300. It should further be appreciated that the arcuate fixationmember 12D is not limited to the illustrated configuration of guidancemembers, and that the fixation body 300 can be differently constructedwith any number of wings 303, flutes 306, keels 308, or any otherguidance members, in any combination.

The fixation body 300 of the arcuate fixation member 12D can define oneor more gripping structures configured to be retain the arcuate fixationmember 12D in an inserted position within an underlying structure, suchas a vertebral body. The gripping structures can include protrusionsdefined on the fixation body 300, such as teeth, spikes, or similarstructures. For example, in the illustrated embodiment, a plurality ofteeth 310 are defined in rows on opposing sides of the fixation body300, in particular in the intermediate portion 300 c of the fixationbody 300 along the edges 300 d. The illustrated plurality of teeth 310are defined by a corresponding plurality of substantially “V” shapednotches 312 defined along the edges 300 d of the fixation body 300. Inthe illustrated embodiment, the notches 312 are defined in paralleldirections with respect to each other, such that the magnitude of anangle β between each notch 312 and the perpendicular reference axis A ismaintained. In alternative embodiments, the notches 312 can be definedin directions that are not parallel with respect to each other, forexample such that the magnitude of the angle β increases with thedistance of each successive notch 312 from the proximal end 300 a of thefixation body 300.

It should be appreciated that the gripping structures are not limited tobeing defined along the edges 300 d of the fixation body 300, and thatgripping structures supplemental to, or in lieu of, the illustratedteeth 310 can alternatively be defined in any other suitable location onthe fixation body 300. It should further be appreciated that thegripping structures are not limited to the gripping structure geometryof the illustrated teeth 310, and that the fixation body 300 canalternatively define any other suitable gripping structure geometry. Itshould further still be appreciated that the number and/or geometry ofthe gripping structures can be defined so to add bone growth surfacearea to the arcuate fixation member 12D.

One or more removal members can be defined in the fixation body 300 ofthe arcuate fixation member 12D, the removal members allowing fordistraction of the arcuate fixation member 12D from an underlyingstructure, such as a vertebral body. For example, in the embodimentillustrated in FIGS. 7A-H, a pair of grooves 314 are defined at theproximal end 300 a of the fixation body 300, the grooves 314 extendinginto the fixation body 300 from the edges 300 d. The illustrated grooves314 are sized to receive complementary members of a removal tool. In analternative embodiment illustrated in FIGS. 7I-J, a single groove 314 isdefined at the proximal end 300 a of the fixation body 300, the groove314 extending into the rear surface 300 f It should be appreciated thatthe arcuate fixation member 12D is not limited to the illustratedremoval members, and that the fixation body 300 can be alternatively bedefined with one or more other suitable removal members.

Referring now to FIGS. 8A-D, an alternative embodiment of theintervertebral implant spacer, or spacer is illustrated. Theintervertebral implant spacer, or spacer 316 defines a spacer body, orbody 318 configured to be implanted into an intervertebral space, thespacer body 318 having an outer wall 318 c that defines an enclosedperimeter of the spacer body 318. In the illustrated embodiment, theouter wall 318 c comprises an anterior wall 318 a extending betweenopposing ends 318 b, a posterior wall 318 d opposite the anterior wall318 a, and opposing side walls 318 e, the side walls 318 e extendingbetween the ends 318 b of the anterior wall 318 a and the posterior wall318 d. The spacer body 318 defines an upper surface 318 f, and a lowersurface 318 g opposite the upper surface. The outer wall 318 c definesan aperture 322 extending into the spacer body 318 through at least oneof the upper or lower surfaces 318 f-g.

A portion, up to an entirety of the anterior wall 318 a can be curvedinwardly toward the posterior wall 318 d, defining an apex of curvature,or apex 320 in the anterior wall 318 a approximately midway between theopposing ends 318 b, as depicted in FIGS. 8A-B. Of course the apex 320can be defined at any other location along the anterior wall 318 a. Inalternative embodiments, the anterior wall 318 a can be straight betweenthe ends 318 b, can be curved outwardly away from the posterior wall 318d, or can define one or more distinct straight portions and/or curvedportions between the ends 318 b, thereby defining a corresponding numberof apices 320 along the anterior wall 318 a. It should be appreciatedthat the shape of the perimeter of the spacer body 318 is not limited tothe illustrated geometry, and that the outer wall 318 c can bedifferently constructed to define an alternatively shaped perimetergeometry of the spacer body 318.

The spacer body 318 can further include an inner wall 318 h, the innerwall 318 h defined so as to divide the aperture 322 defined by the outerwall 318 c into a plurality of apertures 322. For example, in theillustrated embodiment, the inner wall 318 h divides the aperture 322defined by the outer wall 318 c into a pair of apertures 322. Theillustrated inner wall 318 h extends between the apex 320 of theanterior wall 318 a and the outer wall 318 c, in particular between theapex 320 and substantially the midpoint of the posterior wall 318 d. Atleast one additional aperture 322 can be defined between the anteriorwall 318 a and an insert plate, such as insert plate 350 (See FIGS.10A-F) when the insert plate 350 is coupled to the spacer 316. One ormore of the plurality of apertures 322 can be filled with bone growthinducing substances, for example to allow bony growth ingress and/oregress with respect to the spacer 316 and to assist in fusion betweenthe spacer 316 and adjacent vertebral bodies.

In alternative embodiments, the spacer body 318 can be differentlyconstructed, thereby alternatively defining the plurality of apertures322. For example, it should be appreciated that the inner wall 318 h canalternatively be defined to extend between any respective locations onthe anterior wall 318 a and the outer wall 318 c. It should further beappreciated that the spacer body 318 is not limited to a single innerwall 318 h as illustrated, and that alternatively a plurality of innerwalls 318 h having any combination of straight or curved geometries canbe defined, the inner walls 318 h of the plurality of inner walls 318 hextending between a single or multiple locations on the anterior wall318 a and a single or multiple corresponding locations on the outer wall318 c, extending between respective locations on one or more inner walls318 h and the outer wall 318 c, extending between a single or multiplelocations on the outer wall 318 c, extending from a single or multiplelocations on the anterior wall 318 a in a generally outward directionaway from the posterior wall 318 d, or any combination thereof. Itshould further still be appreciated that the respective thicknesses ofthe anterior wall 318 a, the outer wall 318 c, and/or the inner wall 318h can be uniform, or can have one or more portions of varying thickness.

One or more portions, up to an entirety of surfaces of the spacer body318, for instance interior surfaces such as the inner surfaces 318 c′ ofthe outer wall 318 c and/or the inner surfaces 318 h′ of the inner wall318 h, can be configured to allow bony ingrowth into the respectivesurfaces by bone growth inducing substances disposed into the apertures322, for instance to enhance fusion between the spacer 316 and adjacentvertebral bodies and/or to provide a form of secondary fixation betweenan intervertebral implant 400 constructed with the spacer 316 andadjacent vertebral bodies. For example, one or more portions of theinner surface 318 c′ of the outer wall 318 c can be recessed, definingrespective cavities 324 therein. The cavities 324 can be open torespective apertures 322, such that the cavities 324 can be filled withbone growth inducing substances and/or to allow the above-described bonyingrowth into the cavities 324. It should be appreciated that the spacerbody 318 is not limited to the illustrated cavities 324, and that thesurfaces of the spacer body 318 can be differently constructed with anyother geometries in order to allow body ingrowth.

The apertures 322 defined in the spacer body 318 can be configured to bein communication with each other, for example to facilitate biologicalcommunication between bone growth inducing substances in respectiveapertures 322 and/or to allow bony growth ingress and/or egress betweenthe apertures 322. For example, one or more openings, such as openings326 can be defined through the outer wall 318 c and/or the inner wall318 h, the openings 326 placing two or more of the plurality ofapertures 322 in communication with each other. In the illustratedembodiment, a pair of openings 326 are defined through the outer wall318 c, and in particular the anterior wall 318 a. It should beappreciated that the spacer body 318 can alternatively configured todefine one, up to a plurality of openings 326 through the outer wall 318c and/or the inner wall 318 h at any locations along the outer wall 318c and/or the inner wall 318 h.

The spacer 316 is configured to be coupled to an insert plate, such asinsert plate 350. Coupling members can be defined on the spacer body318, the coupling members configured to releasably mate withcomplementary coupling members of an insert plate. For example, in theillustrated embodiment, coupling members in the form of retaininggrooves 328 are defined in the ends 318 b of the anterior wall 318 a,the retaining grooves 328 extending into the spacer body 318 from openends 328 a defined in the lower surface 318 g and terminating in closedends 328 b near the upper surface 318 f The retaining grooves 328 areconfigured to receive complementary retaining members, such as theretaining members 356 defined on the insert plate 350, therein. Theclosed ends 328 b of the retaining grooves 328 can operate to retain theretaining members 356 of an insert plate within the retaining grooves328 and/or act as stops to ensure proper alignment between an insertplate and the spacer 316 during assembly. In an alternative embodiment,the spacer 316 can be constructed such that the retaining grooves 328extend along the entirety of the body 318, such that both ends 328 a-bare open.

Interlocking members can be defined on the coupling members, theinterlocking members configured to be received in releasably lockingengagement with complementary interlocking members defined on theretaining members 356 of the insert plate 350. For example, in theillustrated embodiment, interlocking members in the form of lockingridges 330 are defined in the retaining grooves 328, the locking ridges330 sized to be received in releasably locking engagement withincomplementary locking grooves 358 defined on the retaining members 356of the insert plate 350. In addition to locking the insert plate 350into position with respect to the spacer 316, the interlocking memberscan be configured to facilitate a desired alignment in the transverse,or cranial-caudal direction between the insert plate and the spacer 316.For example, the illustrated locking ridges 330 are located within theretaining grooves 328 at a location approximately equal to the heightwise midpoint of the anterior wall 318 a, thereby ensuring that when theretaining members 356 are inserted into the retaining grooves 328 suchthat the locking ridges 330 are received in the locking grooves 358 (seeFIG. 11B), the spacer 316 and the insert plate will achieve a desiredtransverse alignment with respect to each other.

The upper and lower surfaces 318 f-g of the spacer body 318 can define aplurality of relief members, such as relief grooves 332, the reliefgrooves 332 configured to align with guide apertures 366 of the insertplate 350 (see FIGS. 10A-E) and to partially receive the fixation bodies300 of respective arcuate fixation members 12D therein when anintervertebral implant 400 is assembled from the spacer 316 and aninsert plate 350 and one or more arcuate fixation members 12D areinserted into the guide apertures 366 of the insert plate 350 and driveninto position in an underlying structure, such as a vertebral body. Inthe illustrated embodiment, the relief grooves 332 are concave and aresubstantially smooth and devoid of any protrusions. It should beappreciated that the spacer 316 can be alternatively constructed withoutthe relief grooves 332.

The upper and lower surfaces 318 f-g of the spacer body 318 can beconfigured as bone-engaging surfaces, for example by defining grippingstructures thereon, such as teeth, spikes, or the like. The grippingstructures can be configured to engage adjacent underlying structures,such as the endplates of adjacent vertebral bodies, when theintervertebral implant 400 is inserted into an intervertebral space. Inthe illustrated embodiment, the upper and lower surfaces 318 f-g haveteeth 334 defined thereon. The teeth 334 may be pyramidal, saw toothedor other similar shapes. In alternative embodiments of the spacer 316,portions of, up to the entirety of the upper and/or lower surfaces 318f-g can be substantially smooth and devoid of any gripping structures.

The upper perimeter edge, or upper edge 318 f and the lower perimeteredge, or lower edge 318 g′ of the spacer body 318, defined along theouter periphery of the spacer body 318 where the outer surface of theouter wall 318 c intersects with the upper and lower surfaces 318 f-g,respectively, can be rounded. Rounding the upper and lower edges 318f′-g′ can facilitate easier insertion and/or removal of the spacer 316,and thus the intervertebral implant 400, from an intervertebral space,for example by minimizing required distraction of the end plates ofadjacent vertebral bodies. Distinct portions, up to an entirety of theupper and lower edges 318 f′-g′ can be rounded using a varying radius ofcurvature. For example, in the illustrated embodiment respectiveportions of the upper and lower edges 318 f′-g′ along the posterior wall318 d are rounded with a greater radius of curvature than the remainderof the upper and lower edges 318 f′-g′, such that a “bullet tip” profileis defined on the posterior wall 318 d of the spacer body 318, asdepicted in FIG. 8D. In alternative embodiments, the upper and loweredges 318 f′-g′ can be rounded using a substantially constant radius ofcurvature.

The upper and lower surfaces 318 f-g can be defined as partially, up tofully convex surfaces. In the illustrated embodiment, the convexity ofthe upper and lower surfaces 318 f-g in the anterior-posterior directionbetween the anterior wall 318 a and the posterior wall 318 d differsfrom the convexity of the upper and lower surfaces 318 f-g in thelateral direction between the side walls 318 e. The upper and lowersurfaces 318 f-g are fully convex in the anterior-posterior direction,and exhibit asymmetric convexity with respect to each other, wherein theanterior-posterior convexity of the upper surface 318 f is defined usinga shorter radius than the radius used to define the convexity of thelower surface 318 g. In other words, the upper surface 318 f exhibits agreater amount of curvature than the lower surface 318 g. The upper andlower surfaces 318 f-g are partially convex in the lateral direction,and exhibit symmetric convexity with respect to each other, wherein thelateral convexities of the upper and lower surfaces 318 f-g are equal,or mirror images of each other. In particular, the upper and lowersurfaces 318 f-g define substantially no convexity in the lateraldirection throughout the region C2, and are convex in the lateraldirection in the regions C1 near the side walls 318 e.

It should be appreciated that the geometry of the upper and lowersurfaces 318 f-g is not limited to the convexity of the illustratedembodiment, and that the upper and lower surfaces 318 f-g can be definedwith full or partial convexity in the anterior-posterior and/or lateraldirections, with full or partial concavity in the anterior-posteriorand/or lateral directions, with a combination of partial convexity andconcavity in the anterior-posterior and/or lateral directions, or withno curvature at all (i.e., substantially flat) in the anterior-posteriorand/or lateral directions. It should further be appreciated that theregions C1 and C2 can be defined with wider or narrower widths in thelateral direction. It should further still be appreciated that thegeometry of the upper and lower surfaces 318 f-g can be defined eithersymmetrically or asymmetrically with respect to each other.

Referring now to FIGS. 8C-D, the illustrated embodiment of the spacer316 has a generally wedge shaped side view profile defined by a gradualincrease in height followed by a gradual decrease in height between theanterior wall 318 a and the posterior wall 318 d, and a generallyrectangular front view profile defined by a generally constant heightthroughout the C2 region, and gradually decreasing height throughout theC1 regions between the opposing ends of the C2 region and the side walls318 e. In alternative embodiments the height between the anterior wall318 a and the posterior wall 318 d of the spacer 316 may graduallydecrease, may gradually increase, may have a gradual decrease followedby a gradual increase, or may be generally constant, while the heightbetween the side walls 318 e may increase and/or decrease, or may begenerally constant.

The geometry of the spacer 316, for instance the geometry of the upperand lower surfaces 318 f-g and/or the difference in the height of thebody 318 between the anterior and posterior walls 318 a, 318 d defines alordotic angle θ of the spacer 316. The lordotic angle θ defined by thespacer 316 can be increased and/or decreased by varying the geometry ofthe spacer 316. For example, the lordotic angle θ defined by theillustrated spacer 316 can be increased by heightening the anterior wall318 a of the spacer 316 while maintaining the height of the posteriorwall 318 d. In preferred embodiments, the anterior-posterior convexitydefined by the upper surface 318 f is increased with increasingmagnitude of the lordotic angle θ, while the anterior-posteriorconvexity defined by the lower surface 318 g is maintained. It should beappreciated that when the geometry of the spacer 316 is alternativelyconstructed in order to increase or decrease the lordotic angle θdefined by the spacer 316, the anterior-posterior convexity and/or thelateral convexity of the upper and/or lower surfaces 318 f-g can beincreased or decreased in any combination such that the upper and lowersurfaces 318 f-g are defined the same or differently.

Referring now to FIGS. 9A-D, another alternative embodiment of theintervertebral implant spacer, or spacer is illustrated. Theintervertebral implant spacer, or spacer 336 defines a generally hollowspacer body, or body 338 having an open anterior end 338 a definedbetween opposing ends 338 b, an outer wall 338 c extending around aperimeter of the spacer body 336 between the ends 338 b, and opposingupper and lower plates 338 f-g, the outer wall 338 c extending betweenthe upper and lower plates 338 f-g. The upper and lower plates 338 f-gdefine respective upper and lower surfaces 338 h-i. In the illustratedembodiment, the outer wall 338 c is defined by a posterior wall 338 dopposite the anterior end 338 a and opposing side walls 338 e, the sidewalls 338 e extending between the ends 338 b and the posterior wall 338d. It should be appreciated that the shape of the perimeter of thespacer body 338 is not limited to the illustrated geometry, and that theouter wall 338 c can be differently constructed to define analternatively shaped perimeter geometry of the spacer body 338.

The spacer body 338 can have a plurality of openings, such as apertures340 and/or slots 342 defined therethrough, for example to allow bonygrowth ingress and/or egress with respect to the spacer body 338, thebony growth ingress and/or egress assisting in fusion between the spacer336 and adjacent vertebral bodies and/or providing a form of secondaryfixation between an intervertebral implant 400 constructed with thespacer 336 and adjacent vertebral bodies. In the illustrated embodiment,a plurality of apertures 340 are defined extending through the upper andlower plates 338 f-g, and a plurality of slots 342 are defined extendingthrough the outer wall 338 c. The apertures 340 that extend through eachof the respective plates can have varying diameters with respect to eachother and extend through the plates at locations that define a patternthat can be repeated between the upper and lower plates 338 f-g suchthat the each of the apertures 340 that extend through the upper plate338 f are aligned with corresponding apertures that extend through thelower plate 338 g with respect to central axes defined betweenrespective apertures in a substantially transverse direction to thespacer body 338. The slots 342 are equally sized and elongate in thetransverse direction between the upper and lower plates 338 f-g, and arespaced equally from each other along the outer wall 338 c.

The generally hollow interior of the spacer body 338 can be filled withbone growth inducing substances, for example to allow bony growthingress and/or egress with respect to the spacer body 338 as describedabove. It should be appreciated that spacer body 338 is not limited tothe illustrated apertures 340, that the upper and lower plates 338 f-gcan alternatively be defined with any number of apertures 340 of varyingdiameters and/or locations, and that the apertures 340 on the upper andlower plates 338 f-g, respectively, can be defined the same ordifferently. It should further be appreciated that the spacer body 338is not limited to the illustrated slots 342, that the outer wall 338 ccan alternatively be defined with any number of slots 342 of varyingshapes and/or sizes, and that the slots 342 can be spaced apart fromeach other equally or differently. It should further still beappreciated that the openings defined in the spacer body 338 are notlimited to the illustrated apertures 340 and slots 342, and thatopenings having any other geometry can be defined through the spacerbody 338 at any respective locations, in addition to or in lieu of theapertures 340 and slots 342. It should further still be appreciated thatthe respective thicknesses of the upper plate 338, the lower plate 338 gand/or the outer wall 338 c can be uniform or can have one or moreportions of varying thickness.

The spacer 336 is configured to be coupled to an insert plate, such asinsert plate 350, such that the open anterior end 338 a is disposedbetween the posterior end 338 d and the insert plate. Coupling memberscan be defined on the spacer body 338 of the spacer 336, the couplingmembers configured to releasably mate with complementary couplingmembers of an insert plate. For example, in the illustrated embodiment,coupling members in the form of retaining grooves 344 are defined in theends 338 b of the anterior end 338 a, the retaining grooves 344extending into the spacer body 338 from open ends 344 a defined in thelower surface 338 i and terminating in closed ends 344 b near the uppersurface 338 h. The retaining grooves 344 are configured to receivecomplementary retaining members, such as the retaining members 356defined on insert plate 350, therein. The closed ends 344 b of theretaining grooves 344 can operate to retain the retaining members 356 ofan insert plate within the retaining grooves 344 and/or act as stops toensure proper alignment between an insert plate and the spacer 336during assembly. In an alternative embodiment, the spacer 336 can beconstructed such that the retaining grooves 344 extend along theentirety of the body 338, such that both ends 344 a-b are open.

Interlocking members can be defined on the coupling members, theinterlocking members configured to be received in releasably lockingengagement with complementary interlocking members defined on theretaining members 356 of the insert plate 350. For example, in theillustrated embodiment, interlocking members in the form of lockingridges 346 are defined in the retaining grooves 344, the locking ridges346 sized to be received in releasably locking engagement withincomplementary locking grooves 358 defined on the retaining members 356of the insert plate 350. In addition to locking the insert plate 350into position with respect to the spacer 336, the interlocking memberscan be configured to facilitate a desired alignment in the transverse,or cranial-caudal direction between the insert plate and the spacer 336.For example, the illustrated locking ridges 346 are located within theretaining grooves 344 at a location approximately equal to the heightwise midpoint of the anterior end 338 a, thereby ensuring that when theretaining members 356 are inserted into the retaining grooves 344 suchthat the locking ridges 346 are received in the locking grooves 358 (seeFIG. 11B), the spacer 336 and the insert plate will achieve a desiredtransverse alignment with respect to each other.

The upper and lower plates 338 f-g of the spacer body 338 can define aplurality of relief members, such as relief grooves 339, the reliefgrooves 339 configured to align with guide apertures 366 of the insertplate 350 (see FIGS. 10A-E) and to partially receive the fixation bodies300 of respective arcuate fixation members 12D therein when anintervertebral implant 400 is assembled from the spacer 336 and aninsert plate 350 and one or more arcuate fixation members 12D areinserted into the guide apertures 366 of the insert plate 350 and driveninto position in an underlying structure, such as a vertebral body. Inthe illustrated embodiment, the relief grooves 339 define edges 339 a inthe upper and lower surfaces 338 h-i that are substantially smooth anddevoid of any protrusions. It should be appreciated that the spacer 336can be alternatively constructed without the relief grooves 339.

The upper and lower surfaces 338 h-i of the spacer body 338 can beconfigured as bone-engaging surfaces, for example by defining grippingstructures thereon, such as teeth, spikes, or the like. The grippingstructures can be configured to engage adjacent underlying structures,such as the endplates of adjacent vertebral bodies, when theintervertebral implant 400 is inserted into an intervertebral space. Inthe illustrated embodiment, the upper and lower surfaces 338 h-i haveteeth 348 defined thereon. The teeth 348 may be pyramidal, saw toothedor other similar shapes. In alternative embodiments of the spacer 336,portions of, up to the entirety of the upper and/or lower surfaces 338h-i can be substantially smooth and devoid of any gripping structures.

The upper perimeter edge, or upper edge 338 h′ and the lower perimeteredge, or lower edge 338 i′ of the spacer body 338, defined along theouter periphery of the spacer body 338 where the outer surface of theouter wall 338 c intersects with the upper and lower surfaces 338 h-i,respectively, can be rounded. Rounding the upper and lower edges 338h′-i′ can facilitate easier insertion and/or removal of the spacer 336,and thus the intervertebral implant 400, from an intervertebral space,for example by minimizing required distraction of the end plates ofadjacent vertebral bodies. Distinct portions, up to an entirety of theupper and lower edges 338 h′-i′ can be rounded using a varying radius ofcurvature. For example, in the illustrated embodiment respectiveportions of the upper and lower edges 338 h′-i′ along the posterior wall338 d are rounded with a greater radius of curvature than the remainderof the upper and lower edges 338 h′-i′, such that a “bullet tip” profileis defined on the posterior wall 338 d of the spacer body 338, asdepicted in FIG. 9D. In alternative embodiments, the upper and loweredges 338 h′-i′ can be rounded using a substantially constant radius ofcurvature.

The upper and lower surfaces 338 h-i can be defined as partially, up tofully convex surfaces. In the illustrated embodiment, the convexity ofthe upper and lower surfaces 338 h-i in the anterior-posterior directionbetween the anterior end 338 a and the posterior wall 338 d differs fromthe convexity of the upper and lower surfaces 338 h-i in the lateraldirection between the side walls 338 e. The upper and lower surfaces 338h-i are fully convex in the anterior-posterior direction, and exhibitasymmetric convexity with respect to each other, wherein theanterior-posterior convexity of the upper surface 338 h is defined usinga shorter radius that the radius used to define the convexity of thelower surface 338 i. In other words, the upper surface 338 h exhibits agreater amount of curvature than the lower surface 338 i. The upper andlower surfaces 338 h-i are partially convex in the lateral direction,and exhibit symmetric convexity with respect to each other, wherein thelateral convexity of the upper and lower surfaces 338 h-i are equal, ormirror images of each other. In particular, the upper and lower surfaces338 h-i define substantially no convexity in the lateral directionthroughout the region C4, and are convex in the lateral direction in theregions C3 near the side walls 338 e.

It should be appreciated that the geometry of the upper and lowersurfaces 338 h-i is not limited to the convexity of the illustratedembodiment, and that the upper and lower surfaces 338 h-i can be definedwith full or partial convexity in the anterior-posterior and/or lateraldirections, with full or partial concavity in the anterior-posteriorand/or lateral directions, with a combination of partial convexity andconcavity in the anterior-posterior and/or lateral directions, or withno curvature at all (i.e., substantially flat) in the anterior-posteriorand/or lateral directions. It should further be appreciated that theregions C3 and C4 can be defined with wider or narrower widths in thelateral direction. It should further still be appreciated that thegeometry of the upper and lower surfaces 338 h-i can be defined eithersymmetrically or asymmetrically with respect to each other.

Referring now to FIGS. 9C-D, the illustrated embodiment of the spacer336 has a generally wedge shaped side view profile defined by a gradualincrease in height followed by a gradual decrease in height between theanterior end 338 a and the posterior wall 338 d, and a generallyrectangular front view profile defined by a generally constant heightthroughout the C4 region, and gradually decreasing height throughout theC3 regions between the opposing ends of the C4 region and the side walls338 e. In alternative embodiments the height between the anterior end338 a and the posterior wall 338 d of the spacer 336 may graduallydecrease, may gradually increase, may have a gradual decrease followedby a gradual increase, or may be generally constant, while the heightbetween the side walls 338 e may increase and/or decrease, or may begenerally constant.

The geometry of the spacer 336, for instance the geometry of the upperand lower surfaces 338 h-i and/or the difference in the height of thebody 338 between the anterior end 338 a and the posterior wall 338 ddefines a lordotic angle θ of the spacer 336. The lordotic angle θdefined by the spacer 336 can be increased and/or decreased by varyingthe geometry of the spacer 336. For example, the lordotic angle θdefined by the illustrated spacer 336 can be increased by heighteningthe anterior end 338 a of the spacer 336 while maintaining the height ofthe posterior wall 338 d. In preferred embodiments, theanterior-posterior convexity defined by the upper surface 338 h isincreased with increasing magnitude of the lordotic angle θ, while theanterior-posterior convexity defined by the lower surface 338 i ismaintained. It should be appreciated that when the geometry of thespacer 336 is alternatively constructed in order to increase or decreasethe lordotic angle θ defined by the spacer 336, the anterior-posteriorconvexity and/or the lateral convexity of the upper and/or lowersurfaces 338 h-i can be increased or decreased in any combination suchthat the upper and lower surfaces 338 h-i are defined the same ordifferently.

Referring now to FIGS. 10A-F, alternative embodiments of the insertplate are illustrated. The insert plate, or insert 350 defines a platehaving plate body, or body 352 extending between opposing plate ends 352a, the plate body 352 defining an anterior side 352 b, a posterior side352 c opposite the anterior side, an upper surface 352 d, and a lowersurface 352 e opposite the upper surface. In the illustratedembodiments, the anterior side 352 b defines a curved outer periphery ofthe plate body 352. The plate body 352 can define one or more insertmembers, such as insert slots 354, the insert members configured toreceive the complementary members defined on a delivery, or insertioninstrument. It should be appreciated that the insert members are notlimited to the illustrated insert slots 354, and that the insert memberscan be alternatively defined in accordance with the complementary insertmembers of a respective delivery instrument.

The insert plate 350 is configured to be coupled to a spacer, forinstance the above-described spacers 316 or 336. Coupling members can bedefined on the plate body 352, the coupling members configured toreleasably mate with complementary coupling members of a spacer. Forexample, in the illustrated embodiments, coupling members in the form ofretaining members 356 are defined on the insert plate 350, the retainingmembers being generally “L” shaped, so as to be slidably received in theretaining grooves 328 or 344 of the spacers 316 or 336, respectively. Inthe embodiments illustrated in FIGS. 10A-D and 10F, a “shallow” insertplate 350 is depicted, in which the retaining members 356 are defined onthe plate ends 352 a, the retaining members 356 extending outwardly fromthe posterior side 352 c of the plate body 352. When the shallow insertplate 350 is coupled to the spacer 316 (see FIG. 11A), an aperture 322is defined between the anterior wall 318 a of the spacer body 318 of thespacer 316 and the posterior side 352 c of the plate body 352 of theshallow insert plate. In the embodiment illustrated in FIG. 10E, a“deep” insert plate 350 is depicted, in which the retaining members 356are defined at the ends of side walls 352 f that extend from the plateends 352 a, the retaining members 356 extending outwardly from the endsof the side walls 352 f When the deep insert plate 350 is coupled to thespacer 316, an aperture 322 is defined between the anterior wall 318 aof the spacer body 318 of the spacer 316 and the posterior side 352 cand side walls 352 f of the plate body 352 of the shallow insert plate.The volume of the aperture 322 defined by the spacer 316 coupled to thedeep insert plate 350 is greater than the volume of the aperture 322defined by the spacer 316 coupled to the deep insert plate 350.

Interlocking members can be defined on the coupling members, theinterlocking members configured to receive complementary interlockingmembers, such as the retaining grooves 328 or 344 defined in the spacers316 or 336, respectively, in releasably locking engagement. For example,in the illustrated embodiments, interlocking members in the form oflocking grooves 358 are defined in the ends of the retaining members356. The locking grooves are define a height in the transversedirection, and are of sufficient height to receive the locking ridges330 or 346 of the spacers 316 or 336, respectively, therein. In additionto locking the insert plate 350 into position with respect to a spacer316 or 336, the interlocking members can be configured to facilitate adesired alignment in the transverse direction between the insert plate350 and the respective spacer, as described above. In the illustratedembodiments the locking grooves 358 can define a height that is longerthan the corresponding height of the locking ridges 330 or 346, in orderto allow for a limited amount of translation by the insert plate 350 andthe respective spacer with respect to each other.

It should be appreciated that the insert plate 350 and spacers 316 and336 are not limited to the illustrated configurations of the couplingmembers and/or interlocking members. For example, the retaining grooves328 or 344 could be defined in the insert plate 350, and the retainingmembers 356 could be defined on the spacers 316 or 336. Similarly, thelocking ridges 330 or 346 could be defined on the retaining members 356,and the locking grooves 358 could be defined in the retaining grooves328 or 344. It should further be appreciated that the coupling membersare not limited to the illustrated structures of the retaining grooves328 and 344 or the retaining members 356. For example, the respectiveorientations of the retaining grooves 328 or 344 and the retainingmembers 356 could be reversed with respect to the lateral direction. Itshould further still be appreciated that the insert plate 350 andspacers 316 and 336 are not limited to the illustrated coupling membersand/or interlocking members, and that any alternative structures can beemployed to couple and/or lock the spacers 316 or 336 and the insertplate 350 with respect to each other.

The upper and lower surfaces 352 d-e of the plate body 352 can beconfigured as bone-engaging surfaces, for example by defining grippingstructures thereon, such as teeth, spikes, or the like. The grippingstructures can be configured to engage adjacent underlying structures,such as the endplates of adjacent vertebral bodies, when theintervertebral implant 400 is inserted into an intervertebral space. Inthe embodiments illustrated in FIGS. 10A-D and 10F, portions of theupper and lower surfaces 352 d-e have teeth 360 defined thereon. Theteeth 360 may be pyramidal, saw toothed or other similar shapes. In theembodiment illustrated in FIG. 10E, the entireties of the upper andlower surfaces 352 d-e have teeth 360 defined thereon. The upper andlower edges 352 d′-e′ of the upper and lower surfaces 352 d-e,respectively, can be rounded. Rounding the upper and lower edges 352d′-e′ can facilitate easier insertion and/or removal of the insert plate350, and thus the intervertebral implant 400, from an intervertebralspace, for example by minimizing required distraction of the end platesof adjacent vertebral bodies. Distinct portions, up to an entirety ofthe upper and lower edges 352 d′-e′ can be rounded using substantiallyconstant or varying radii of curvature.

The geometry of the upper and lower surfaces 352 d-e of the plate body352 may be defined to generally conform the insert plate 350 to thegeometry of the spacers 316 or 336. For example, in the illustratedembodiments, the upper and lower surfaces 352 d-e are defined aspartially convex surfaces. In particular, the upper and lower surfaces352 d-e exhibit lateral convexity in the regions C5 near the plate ends352 a, the convexity on the upper and lower surfaces 352 d-e beingsymmetric with respect to each other. The height of the insert plate 350gradually decreases between the anterior and posterior sides 352 b-c,respectively (see FIGS. 12A-B). It should be appreciated that the insertplate 350 is not limited to the illustrated geometry of the upper andlower surfaces 352 d-e, and that the upper and lower surfaces 352 d-ecan be defined with full or partial convexity in the anterior-posteriorand/or lateral directions, with full or partial concavity in theanterior-posterior and/or lateral directions, with a combination ofpartial convexity and concavity in the anterior-posterior and/or lateraldirections, or with no curvature at all (i.e., substantially flat) inthe anterior-posterior and/or lateral directions. It should further beappreciated that the regions C5 can be defined with wider or narrowerwidths in the lateral direction. It should further still be appreciatedthat the geometry of the upper and lower surfaces 352 d-e can be definedeither symmetrically or asymmetrically with respect to each other. Itshould further still be appreciated that the height of the insert plate350 between the anterior and posterior sides 352 b-c, respectively, maygradually increase, may have a gradual decrease followed by a gradualincrease, may have a gradual increase followed by a gradual decrease, ormay be generally constant, and that the height between the plate ends352 a may increase and/or decrease, or may be generally constant.

The anterior side 352 b of the plate body 352 can define a concaverecess 362, the recess configured to receive the complementary convexsurface of a blocking plate, such as the blocking plate 132 describedabove. The insert plate 350 can also have a central bore 364 definedtherethrough, the central bore 364 defining a threaded inner boresurface 364 a, the threads of the inner bore surface 364 a configured toengage complementary threads of a locking screw, such as the lockingscrew 138 described above.

The plate body 352 can also have one or more guide apertures 366 definedtherethrough, the guide apertures 366 configured to slidably receivebone fixation members therein, such as the arcuate fixation members 12D,and to define insertion trajectories into underlying structures for thefixation members received therein. In the illustrated embodiments, theguide apertures 366 are defined as substantially straight guideapertures extending through the plate body 352 from within the concaverecess 362 in the anterior side 352 b through the posterior side 352 c.The guide apertures 366 can have substantially uniform cross sectionalgeometries that are defined to substantially conform to the crosssectional geometry of the intermediate portion 300 c of the body 300 ofthe arcuate fixation member 12D.

The guide apertures 366 and/or the arcuate fixation members 12D can beconfigured to releasably lock respective arcuate fixation members 12D ininserted positions within the guide apertures 366. For example, in theillustrated embodiments, recessed ledges 368 are defined in the surfaceof the concave recess 362 around a portion of the perimeter of each ofthe guide apertures 366, the recessed ledges 368 configured to receivethe lower surfaces 304 b of the heads 304 of respective arcuate fixationmembers 12D when the arcuate fixation members 12D are inserted intorespective guide apertures 366. One or more surfaces within the recessedledges 368 can be configured to engage with complementary taperedsurfaces defined on the heads 304 of respective arcuate fixation members12D, for instance surfaces 304 c, thereby locking the arcuate fixationmembers 12D in respective inserted positions. In an alternativeembodiment, the cross sectional geometries of the guide apertures 366can be tapered between the anterior and posterior sides 352 b-c of theplate body 352, such that the arcuate fixation members 12D are press fitwithin the guide apertures 366 as they are inserted. Of course thearcuate fixation members 12D and/or the guide apertures 366 can beconfigured such that no locking affect is imparted therebetween. Itshould be appreciated that the above-described blocking plate 132 andlocking screw 138 can be employed to secure the arcuate fixation members12D within inserted positions in the guide apertures, whether or not thearcuate fixation members 12D and/or the guide apertures 366 areconfigured to releasably lock with respect to each other.

The guide apertures 366 can be disposed about the central bore 364 atany desired locations and can define any insertion trajectories asappropriate. In the illustrated embodiments, the guide apertures 366 aredefined in opposing quadrants around the central bore 364, with twoguide apertures 366 located near the upper surface 352 d and definingtwo generally outward and cranial insertion trajectories, and two guideapertures 366 located near the lower surface 352 e and defining twogenerally outward and caudal insertion trajectories. It should beappreciated that the insert plate 350 is not limited to the illustratedconfiguration of guide aperture 366 locations and insertiontrajectories, and that the insert plate 350 can be differentlyconfigured with any number of guide apertures 366 defined at anylocations on the plate body 352 and having any insertion trajectories.It should further be appreciated that the guide apertures 366 can bestraight, curved along one or more locations between the anterior andposterior sides 352 b-c, respectively, or any combination thereof.

Referring now to FIGS. 11A-12C, an example embodiment of anintervertebral implant 400 constructed from components of theintervertebral implant system 100 is illustrated. In particular, theintervertebral implant 400 includes an insert plate 350 coupled to aspacer 316. The intervertebral implant 400 can further include one ormore arcuate fixation members 12D, a blocking plate 132, and/or alocking screw 138 (see FIGS. 14A-B), for example in accordance with theinsert plate 350 provided. It should be appreciated that theintervertebral implant 400 can be alternatively constructed with thespacer 336, that the insert plate 350 can be provided as a shallowinsert plate 350 or a deep insert plate 350 as described above, and thatthe insert plate 350 can be constructed with or without the guideapertures 366. In the illustrated embodiment, the spacer 316, and inparticular the outer wall 318 c, is constructed so that the width W ofthe spacer 316 in the lateral direction substantially conforms to thewidth of the insert plate 350 in the lateral direction. The insert plate350 coupled to the spacer 316 in the illustrated embodiment is a shallowinsert plate 350, as described above. When coupled to each other in anassembled configuration, the spacer 316 and the insert plate 350 definea “footprint” of the intervertebral implant 400, the footprint referringto the shape of the outer periphery of the intervertebral implant 400 asdefined by the outer wall 318 c of the spacer 316 and the anterior side352 b of the insert plate 350.

It should be appreciated that the intervertebral implant 400 is notlimited to the illustrated footprint, and that the spacer 316 and/or theinsert plate 350 can be differently constructed to define alternativefootprints of the intervertebral implant 400. For example, the deepinsert plate 350, described above, can be coupled to the spacer 316 inlieu of the shallow insert plate 350, defining an intervertebral implant400 having a larger footprint than the footprint defined by the shallowinsert plate 350 coupled to the spacer 316 (see FIG. 12A). Additionally,when the deep insert plate 350 is coupled to the spacer 316, theaperture 322 defined by the anterior wall 318 a of the spacer 316 andthe posterior side 352 c of the insert plate 350 is larger than theequivalent aperture 322 defined when the shallow insert plate 350 iscoupled to the spacer 316. The spacer 316 can also be differentlyconstructed, for example by defining the outer wall 318 c withalternative widths W of the spacer 316 in the lateral direction and/ordepths D of the spacer 316 in the anterior-posterior direction. Forinstance, the spacer 316 depicted in FIGS. 12B-C has a greater width anddepth than the spacer 316 depicted in FIGS. 11A and 12A, therebydefining intervertebral implants 400 with larger footprints when coupledto the shallow or deep insert plates 350, as depicted in FIGS. 12B-C,respectively. It should be appreciated that the spacer 336 can similarlybe differently constructed with varying widths and/or depths, therebydefining intervertebral implants 400 with differently sized footprintswhen coupled to the shallow or deep insert plates 350.

Referring now to FIGS. 13A-B, in addition to providing for theconstruction of intervertebral implants 400 defining varying footprints,the components of the intervertebral implant system 100 also provide forthe construction of intervertebral implants 400 defining varyinglordotic angles. The lordotic angle θ of an intervertebral implant 400can be defined by the geometry of its component parts, such as thesurface geometry of the components and/or the height of the components.In the embodiment illustrated in FIG. 13A, a spacer 316 is coupled to aninsert plate 350 having a height that is shorter than the height of thespacer 316 at the ends 318 b of the anterior wall 318 a. The lordoticangle θ of the intervertebral implant 400 is defined by the spacer 316.In an alternative embodiment illustrated in FIG. 13B, the spacer 316 isidentical to the spacer 316 used in constructing the intervertebralimplant 400 depicted in FIG. 13A, but is coupled to an insert plate 350having a height that is taller than the height of the spacer 316 at theends 318 b of the anterior wall 318 a. The increased height of theinsert plate 350 produces a corresponding increase in the magnitude ofthe lordotic angle θ of the intervertebral implant 400. It should beappreciated that the lordotic angle defined by intervertebral implants400 constructed using the spacer 336 can similarly be varied based uponthe height of the insert plate 350 coupled thereto. It should further beappreciated that the spacers 316 and/or 336 can be differentlyconstructed with varying heights, thereby defining intervertebralimplants 400 with different lordotic angles when coupled to identicalinsert plates 350.

Referring now to FIGS. 14A-B, an example intervertebral implant 400 isillustrated in an exploded view containing selected components of theintervertebral implant system 100, and in an assembled configurationafter being inserted into an intervertebral space, respectively. Thecharacteristics of the assembled intervertebral implant 400, forinstance the footprint and/or lordotic angle defined thereby, can betailored when selecting the individual components, for example inaccordance with region of the spine where the intervertebral implant 400will be inserted, particular patient anatomy, and the like. Thus, theintervertebral implant system 100 can be described as a modularintervertebral implant system 100 that allows a surgeon to construct apatient specific intervertebral implant 400. In the illustrated example,the spacer 316 and insert plate 350 can be selected based upon thedesired footprint and/or or lordotic angle that will be defined by theintervertebral implant. The quantity and length of arcuate fixationmembers 12C and/or 12D can also be selected.

Once the components of the intervertebral implant system 100 have beenselected, the spacer can be coupled to the insert plate by inserting theretaining members of the insert plate into the retaining grooves on thespacer and advancing the retaining members until the locking ridges arereceived in the locking grooves. The intervertebral implant 400 can thenbe filled with bone growth inducing substances as described above andinserted into an intervertebral space between adjacent vertebral bodiesusing an insertion, or delivery instrument (not shown). The arcuatefixation members can then be inserted into the guide apertures anddriven into place within the adjacent vertebral bodies. Once the arcuatefixation members are inserted, a blocking plate can be disposed into theconcave recess in the insert plate and a locking screw can be driventhrough the blocking plate and into the insert plate, thereby securingthe intervertebral implant in an assembled and inserted configuration.

It should be appreciated that a variety of kits can be provided thatcontain one or more components of the intervertebral implant system 100.The components of the kits may be configured the same or differently.For example, within a single kit, arcuate fixation members 12C and/or12D may be provided that have different lengths, different radii ofcurvature, differing head configurations, differing cross sectionalgeometries, and so on, depending for example on the type of procedurebeing performed by a surgeon, or on the particular anatomies ofindividual patients. The kits may also be configured differently withrespect to which components of the intervertebral implant system 100 areincluded in the kits. For example, a kit for the intervertebral implantsystem 100 may include arcuate fixation members 12C and/or 12D ofdifferent lengths, radii of curvature, and/or features, and may includeone or more of spacers 108, 316 and/or 336 having different heights,perimeter geometries, or surface geometries, or defining differentlordotic angles, insert plates 116 or 350 having different heights,perimeter geometries, surface geometries, and guide apertures, blockingplates 132, or locking screws 138.

Although arcuate fixation members and the other components of theintervertebral implant system 100 have been described herein withreference to preferred embodiments or preferred methods, it should beunderstood that the words which have been used herein are words ofdescription and illustration, rather than words of limitation. Forexample, it should be noted that although the intervertebral implantsystem 100 has been described herein with reference to particularstructure, methods, and/or embodiments, the scope of the instantdisclosure is not intended to be limited to those particulars, butrather is meant to extend to all structures, methods, and/or uses of theintervertebral implant system 100. Those skilled in the relevant art,having the benefit of the teachings of this specification, may effectnumerous modifications to the intervertebral implant system 100 asdescribed herein, and changes may be made without departing from thescope and spirit of the instant disclosure, for instance as recited inthe appended claims.

What is claimed:
 1. A method for fixing an intervertebral implant in an intervertebral space defined between an upper vertebral body and a lower vertebral body, the method comprising the steps of: inserting a spacer body of the intervertebral implant into the intervertebral space so that upper and lower bone-engaging surfaces of the spacer body engage the upper and lower vertebral bodies, respectively, wherein a fixation plate of the intervertebral implant is coupled to the spacer body, wherein the fixation plate comprises retaining members which are received in complementary retaining grooves of the spacer body to couple the fixation plate to the spacer body opposite a posterior wall of the spacer body, the fixation plate defining a plurality of guide apertures extending therethrough for receiving a plurality of curved bone fixation members, wherein the spacer body includes a pair of side walls that extend between the posterior wall and the fixation plate, the spacer body defines an aperture that extends from the lower bone-engaging surface to the upper bone-engaging surface and extends between the pair of side walls along a first direction and extends between the posterior wall and the fixation plate along a second direction that is perpendicular to the first direction, the posterior wall defining an inner surface that faces toward the fixation plate, the inner surface defining at least one cavity that is open to the aperture, the at least one cavity defining a recessed surface that is positioned intermediate the inner surface and an outer surface of the posterior wall; disposing bone growth inducing substance into the aperture such that at least some of the bone growth inducing substance extends within the at least one cavity; and inserting a plurality of curved bone fixation members into respective ones of the plurality of guide apertures such that each curved bone fixation member fixes the intervertebral implant to one of the upper and lower vertebral bodies.
 2. The method of claim 1, wherein the disposing step comprises packing the bone growth inducing substance into the aperture prior to the inserting step.
 3. The method of claim 1, wherein the bone growth inducing substance is disposed into the aperture to fill the aperture and allowing boney ingrowth into the at least one cavity.
 4. The method of claim 1, wherein the at least one cavity is elongate along the first direction.
 5. The method of claim 1, wherein the at least one cavity comprises a plurality of cavities.
 6. The method of claim 1, wherein at least one of the curved bone fixation members of the plurality of curved bone fixation members is rotationally fixed in a respective one of the plurality of guide apertures as the at least one curved bone fixation member is inserted into engagement with one of the upper and lower vertebral bodies.
 7. The method of claim 6, wherein the at least one curved bone fixation member is guided along an insertion trajectory through the one of the upper and lower vertebral bodies, and wherein a guidance member disposed at least partially along a distal end of the at least one curved bone fixation member facilitates the guiding.
 8. The method of claim 7, wherein the guidance member comprises a keel extending from the distal end, at least one wing disposed adjacent the keel, and a flute disposed between the keel and the at least one wing.
 9. The method of claim 8, wherein the guidance member further comprises a second wing disposed adjacent the keel, such that the keel is disposed between the wings.
 10. The method of claim 8, wherein the flute extends substantially parallel to the insertion trajectory.
 11. The method of claim 7, further comprising driving a curved intermediate portion of the at least one curved bone fixation member, the curved intermediate portion extending between a proximal end and the distal end of the at least one curved bone fixation member, wherein the driving step comprises sliding the curved intermediate portion through the respective one of the plurality of guide apertures such that a cross-sectional shape of the curved intermediate portion resides within a conforming cross-sectional shape of the respective one of the plurality of guide apertures.
 12. The method of claim 7, wherein a tapered tip of the at least one curved bone fixation member cuts into the one of the upper and lower vertebral bodies during insertion.
 13. The method of claim 6, further comprising positioning at least one blocking member with respect to the plurality of curved bone fixation members such that a portion thereof extends behind a proximal end of the at least one curved bone fixation member, thereby blocking the at least one curved bone fixation member from backing out of the respective one of the plurality of guide apertures.
 14. A method for implanting an intervertebral implant in an intervertebral space, the method comprising the steps of: inserting a spacer body of the intervertebral implant into the intervertebral space so that upper and lower bone-engaging surfaces of the spacer body engage upper and lower vertebral bodies, respectively, wherein a fixation plate of the intervertebral implant is coupled to the spacer body, the fixation plate comprises retaining members which are received in complementary retaining grooves of the spacer body to couple the fixation plate to an anterior wall of the spacer body opposite a posterior wall of the spacer body, the fixation plate defining a plurality of guide apertures extending therethrough for receiving a plurality of bone fixation members, the spacer body includes a pair of side walls that are spaced from each other along a first direction, the sidewalls extending between the anterior and posterior walls along a second direction that is perpendicular to the first direction, the spacer body defining a first aperture and a second aperture that each extend from the lower bone-engaging surface to the upper bone-engaging surface along a third direction that is perpendicular to the first and second directions, wherein the first and second apertures are located between the side walls along the first direction and between the anterior and posterior walls along the second direction, the spacer body further defining an inner wall that extends between the anterior and posterior walls along the second direction and separates the first and second apertures, disposing bone growth inducing substance into the first and second apertures such that at least some of the bone growth inducing substance extends within first and second cavities defined within an inner surface of the posterior wall, wherein the first cavity is open to the first aperture and the second cavity is open to the second aperture, and each of the first and second cavities defines a recessed surface positioned intermediate the inner surface and an outer surface of the posterior wall; and inserting a plurality of bone fixation members into respective ones of the plurality of guide apertures such that each bone fixation member fixes the intervertebral implant to one of the upper and lower vertebral bodies.
 15. The method of claim 14, wherein the disposing step comprises packing the bone growth inducing substance into the first and second apertures prior to the inserting step, and wherein the bone growth inducing substance is disposed into the first and second apertures to fill the first and second apertures and allow boney ingrowth into the first and second cavities.
 16. The method of claim 14, wherein at least one of the bone fixation members of the plurality of bone fixation members is rotationally fixed in a respective one of the plurality of guide apertures as the at least one bone fixation member is inserted into engagement with one of the upper and lower vertebral bodies.
 17. The method of claim 16, wherein the plurality of bone fixation members are each curved bone fixation members.
 18. The method of claim 17, wherein the at least one bone fixation member is guided along an insertion trajectory through the one of the upper and lower vertebral bodies, and wherein a guidance member disposed at least partially along a distal end of the at least one bone fixation member facilitates the guiding.
 19. The method of claim 18, wherein the guidance member comprises a keel extending from the distal end, at least one wing disposed adjacent the keel, and a flute disposed between the keel and the at least one wing. 